Most aspects of the story are not what you would expect upon first reading of the text. Consider:
The story is set in and around the town of Summit - a term that would usually be applied to the peak of a mountain, but this town is flat.
Johnny, the ten-year-old boy who is the kidnapping victim, becomes the person in charge, terrorizing his kidnappers with his constant talk and activity and physical assaults against them.
Johnny's father not only refuses to pay the ransom for his son's release but succeeds in collecting a payment from Sam and Bill before he agrees to allow Johnny to return home.
Unlike most kidnapping victims who are happy to be released from captivity, Johnny doesn't want to leave the cave and his new playmates and chases after them instead of eagerly returning home.